BRPI0721604B1 - METHOD FOR MANUFACTURING AN INTEGRATED MULTILONGARIN TORQUE BOX STRUCTURE OF AIRCRAFT COMPOSITE MATERIAL - Google Patents

Abstract

integrated multilongarine twist box made of composite material. The present invention relates to an integrated multilongarine torsion box structure of composite aircraft material, comprising a lower liner (12), an upper liner (11), several stringers (9), each of which comprise, for A rope (13) and a web (14), several longitudinal reinforcers (10) in the lower sheath (12) and several longitudinal reinforcers (10) in the upper sheath (11), characterized in that the housing structure of integrated torsion is obtained by joining U-shaped unitary structural elements (15), U-shaped unitary structural elements (16) with a flap and c-shaped unitary structural elements (17) with a flap. The invention also relates to a method for the manufacture of an integrated multilonger twistbox structure of aircraft composite material.

Description

(54) Title: METHOD FOR THE MANUFACTURE OF AN INTEGRATED MULTILONGARY TORSION BOX STRUCTURE OF COMPOSITE MATERIAL FOR AIRCRAFT (51) Int.CI .: B29C 70/34; B29D 99/00; B64C 1/06; B64C 3/18 (73) Owner (s): AIRBUS OPERATIONS, S.L.

(72) Inventor (s): MARÍA PILAR MUNOZ LÓPEZ; FRANCISCO JOSÉ CRUZ DOMÍNGUEZ; JOSÉ DAVID CANO CEDIEL

1/10

Descriptive Report of the Invention Patent for METHOD FOR THE MANUFACTURE OF AN INTEGRATED MULTILONGARINE TORSION BOX STRUCTURE OF COMPOSITE MATERIAL FOR AIRCRAFT.

Field of the Invention [001] The present invention relates to a torsion box structure of integrated multi-lingual composite material, as well as a method for manufacturing that structure.

Background of the Invention [002] It is commonly known that the aeronautical industry requires structures that, on the one hand, can withstand the loads to which they are subjected, in accordance with the requirements of high strength and rigidity and, on the other hand, are so light as possible. A result of this requirement is the increasingly widespread use of composite materials in primary aircraft structures, involving significant weight savings compared to the use of metallic materials.

[003] The main structure to support surfaces of airplanes is formed by a leading edge, a torsion box and a trailing edge. The torsion box of an aircraft, in turn, is formed by several structural elements. Typically, the process of making a torsion box is considerably manual and is carried out in a number of steps. The structural elements that form the box are manufactured separately and are mechanically joined with the aid of complicated templates to obtain the necessary tolerances, which are given by the aerodynamic and structural requirements. This involves different assembly stations and a large number of joining elements, which leads to weight disadvantages, high production and assembly costs, greater logistical capacity required and poor aerodynamic quality on surfaces.

Petition 870180012942, of 02/19/2018, p. 5/20

2/10 external. If the parts are made of composite material, they are manufactured by stacking the different layers of fibers and thus form the desired element, layer by layer. At this point, the composite material requires a very expensive curing process to obtain all of its properties.

[004] For this reason, recently, great efforts have been made to obtain an increasing level of integration in the production of composite torsion boxes and, thus, to prevent the aforementioned disadvantages. The problem mainly consists in generating sufficient pressure in all elements during the joint curing process.

[005] In this way, there are several known documents describing manufacturing methods that achieve the integration of typical structural elements, with the help of special curing templates, assembly of the remaining elements in the following assembly stages. This is the case of US patent No. 5216799 (integration of ribs with stringers), patent document EP 1074466A1 (integration of ribs) and US patent No. 5735486 (integration of longitudinal reinforcers - coatings). Other levels of integration are achieved with the solutions presented in US patent No. 6237873B1, describing the manufacture of closed cross sections and their subsequent joining and in US patent No. 6190484B1, where contiguous boxes are joined together to be cured together.

[006] Patent documents EP 0582160A1, US 6896841B2, US 5454895, WO 2004 / 000643A2 and US 5817269 are focused on the template system to allow the manufacture of the complete part in a single cure with good quality, either with templates that are inflated during curing or using the difference in thermal expansion of different materials to exert pressure during curing at high temperatures.

Petition 870180012942, of 02/19/2018, p. 6/20

3/10 [007] However, all of these solutions start from the basis of individual pre-stacking of the basic structural elements and curing them together with the appropriate templates, which is not a complete real integration, while at the same time, the manufacturing costs are high, due to the high number of parts to be stacked, and there is still a non-uniform load passage between the stacked elements.

[008] The present invention aims to solve these disadvantages.

Summary of the Invention [009] Therefore, the present invention relates to a torsion box structure of integrated multi-lingual composite material for aircraft, comprising the following structural elements:

- bottom lining

- top coating

- several stringers, which, in turn, are formed by:

- Rope

- Soul

- several longitudinal reinforcers in the top coating

- several longitudinal reinforcers in the bottom coating.

[0010] The anterior torsion box is created starting from individual elements in composite material, which are already integrated from the stacking and which, in turn, assume several structural functions (they are part of the longitudinal reinforcement, of the stringer and / or at the same time), obtaining a complete integrated structure required, by joining several of these elements, before the final curing phase. This involves having all the advantages of an integrated structure, in addition to greater savings in

Petition 870180012942, of 02/19/2018, p. 7/20

4/10 manufacturing, since there are fewer parts to be stacked and a more uniform load passage between the stacked elements.

[0011] The present invention also relates to a method for manufacturing a torsion box structure of integrated multilongarines of composite material for aircraft, comprising the following steps:

1) stacking of a compound with or without integrated longitudinal reinforcers, carried out by any manual or automatic process;

2) curvature of the laminate or laminates by applying the appropriate cycle and with the appropriate template;

3) joining the various elements that will form the desired structure;

4) consolidation of the complete structure through the application of a single pressure and temperature cycle.

[0012] Other characteristics and advantages of the present invention will be understood from the following detailed description of an illustrative modality of its object in relation to the attached figures. Description of the Drawings [0013] Figure 1 shows a torsion box of a horizontal aircraft stabilizer with a typical multi-rib structure. [0014] Figure 2a shows the interior of a military aircraft wing with a typical multilong structure.

[0015] Figure 2b shows a cross section of the interior of a military aircraft wing with a typical multilong structure.

[0016] Figure 2c shows a typical stringer of a military aircraft wing with a typical multilongarine structure.

[0017] Figure 3 shows, schematically, a cross-section of a multi-lingual box with longitudinal reinforcers, object of the present invention.

Petition 870180012942, of 02/19/2018, p. 8/20

5/10 [0018] Figure 4 shows, schematically, a cross section of a box of multilongarines with structural elements that form the same, object of the present invention.

[0019] Figure 5 shows, schematically, a structural element in the form of U-type 1, forming a multi-lingual box with longitudinal reinforcers, object of the present invention.

[0020] Figure 6 shows, schematically, a type 2 U-shaped structural element, with a flap forming a multilong box with longitudinal reinforcers, object of the present invention.

[0021] Figure 7 shows, schematically, a structural element in the form of C-type 3, with a flap forming a multilong box with longitudinal reinforcers, object of the present invention.

[0022] Figure 8 shows the flat stacking of a structural element forming a multilong box with longitudinal reinforcers, object of the present invention.

[0023] Figure 9 shows, schematically, the curvature of a structural element forming a multilong box with longitudinal reinforcers, object of the present invention.

[0024] Figure 10 shows the result of a curvature and a possible second curvature of a structural element forming a multilong box with longitudinal reinforcers, object of the present invention.

[0025] Figure 11 shows the junction of two structural elements, forming longitudinal reinforcers in the form of I and panel, forming a multi-lingual box with longitudinal reinforcers, object of the present invention.

[0026] Figure 12 shows the junction of two structural elements, forming longitudinal reinforcers in the shape of T and stringers and fatherPetition 870180012942, of 02/19/2018, p. 9/20

6/10 level, forming a multi-lingual box with longitudinal reinforcers, object of the present invention.

[0027] Figure 13 shows the position of the fuses joining two structural elements forming a box of multilongarines, with longitudinal reinforcers, object of the present invention

Detailed Description of the Invention [0028] The invention relates to a torsion box structure of integrated multi-core composite materials with longitudinal reinforcers, with a T-shaped or I-shaped cross section, all being co-cured. The composite material can be carbon fiber and glass fiber with thermosetting or thermoplastic resin. The main field of application is the aeronautical structure with support surfaces, although they can also be applied to other structures with similar characteristics.

[0029] An integrated structure is one in which the different structural elements subjected to different stresses (shear stress, normal stress, etc.) are manufactured at once or start from a single part. This is another advantage of using composite materials because, due to their independent layer conditions, which can be stacked in the desired way, they offer the possibility of additional integration to the structure, which still causes a cost savings, since there are fewer individual parts to be assembled.

[0030] The main structure of support surfaces of airplanes is formed by a leading edge, a torsion box and a trailing edge. The torsion box is a typical structure formed by an upper panel and a lower panel with thin walls and spars front 2 and rear 3. Other structural elements, such as ribs 4 and longitudinal reinforcers 5, can be inside the torsion box, reinforcing elements also being necessary in alPetição 870180012942, of 02/19/2018, p. 10/20

7/10 guns of these components, given their extreme fineness.

[0031] Depending on the structural requirements and the manufacturing requirements, maintenance capacity, certification, etc., all these elements may or may not be essential and may be more or less effective.

[0032] The structure currently most used for a torsion box comprises, internally, several transverse ribs 4 between the front 2 and rear 3 stringers, ribs whose main functions are to provide torsional rigidity, to limit the linings and reinforcements longitudinally, in order to relativize the arching loads and maintain the shape of the aerodynamic surface (see figure 1). This structure is usually still reinforced longitudinally by reinforcements 5.

[0033] Another structural concept of a torsion box is the multilongar (see figure 2), where the ribs are distributed and the multilongarins 6 are introduced, stringers that comprise, in turn, a rope or leg 7 and core 8.

[0034] The object of the present invention is the creation of a highly integrated torsion box structure, without ribs, with several longitudinal reinforcers, in the form of I or T, 10 (longitudinal reinforcers) and stringers 9, to obtain a structure effective with respect to resistance / rigidity and low weight. An integrated structure can thus mean savings in manufacturing costs and an improvement in quality.

[0035] The multilong box, object of the present invention, is formed by coatings 11 and 12, which are the elements that close the box at the top and bottom and are characterized by the fact that they mainly support compression - traction and shear loads on the plane. Longitudinal reinforcers 10 were introduced to obtain sufficient rigidity for these panels 11 and 12 and stabilize the

Petition 870180012942, of 02/19/2018, p. 11/20

8/10 even against bending, without increasing its thickness. Longitudinal reinforcers also take part of the longitudinal flows resulting from the moments of curvature.

[0036] On the other hand, there are multilongarines 9 which, like coatings 11 and 12, are typical thin-walled structures. They must withstand mainly curvature and torsion loads. In a simplified way, the resulting shear flows must be supported by the stringer core 9, while the stringer legs or ropes 9 must withstand the tensile and compression loads resulting from the curvature.

[0037] Therefore, from a structural point of view, the box comprises the following elements:

- bottom coating 12

- top coating 11

- several stringers 9, which in turn are formed by:

- string 13

- soul 14

- several longitudinal reinforcers 10 in the upper coating 11

- several longitudinal reinforcers 10 in the lower lining 12.

[0038] The process for producing a torsion box according to the present invention is carried out in such a way that the U-shaped elements 15 (type 1), the U-shaped elements 16 with a flap (type 2) or the C 17-shaped elements with a flap (type 3) are formed individually, when the fiber layers 20 are stacked. Each of these elements 15, 16, 17 assumes several structural functions, which, when joined, give rise to the desired complete configuration. In a final step, the entire component is cured in a single cycle and a multi-lingual box structure

Petition 870180012942, of 02/19/2018, p. 12/20

9/10 fully integrated including longitudinal reinforcers 10 is obtained.

[0039] The detailed steps of the process for the manufacture of a composite multi-core twist box will be described below, a process that is divided into four steps:

[0040] In step 1, the layers of carbon fiber or fiberglass 20 are stacked separately flat, layers that form each element 15, 16, 17. These stacks can, perfectly, have reinforcers 19, be subjected to changes plan and have stacking changes according to whether later they will be part of a panel 11, 12, of the stringer 9 or of the longitudinal reinforcement 10, as shown in figure 8.

[0041] In step 2, the stack is curved. This curvature can be performed in different ways, preferably by applying a vacuum and temperature cycle 22, molding the stack with the desired geometry using the appropriate template 21, template that copies its internal geometry, as shown in the figure 9.

[0042] If a longitudinal I-shaped reinforcement is required, it might be necessary to bend a second time (figure 10) to obtain a type 2 element 16.

[0043] In step 3, the different elements are joined to form the integrated structure, according to figures 11 and 12. It may be necessary to introduce wicks (strips of unidirectional fibers, which must be of the same material as that used in the piles or compatible material) at that stage to prevent gaps and thus ensure an optical co-cure (figure 13). It is also possible that continuous batteries are required outside the box, which would correspond to pure coatings, elements 18 of type 4.

[0044] In step 4, the complete structure is cured by applying a pressure and temperature cycle, with the aid of the system

Petition 870180012942, of 02/19/2018, p. 13/20

10/10 of adequate template, which allows the adequate compaction of all areas of the structure.

[0045] The modifications included within the scope defined by the following claims can be introduced in the modality that has just been described.

Petition 870180012942, of 02/19/2018, p. 14/20

1/2

Claims (7)

1. Method for the manufacture of a torsion box structure of integrated multi-lingual composite material for aircraft, comprising the steps of, a) separately stack the fiber layers (20) flat forming U-shaped elements (15), U-shaped elements (16); C-shaped elements (17) with a flap; b) bend the stack: c) joining the different elements (15, 16, 17) to shape the integrated multi-lingual torsion box structure; and d) cure the complete structure through the application of a pressure and temperature cycle, with the aid of a template system (21), allowing the adequate compaction of all areas of the structure, characterized by the fact of unidirectional fiber strips called wicks are introduced in step c) of joining different elements (15, 16, 17) to shape the integrated multongarine torsion box structure. 2. Method for the manufacture of a torsion box structure of integrated multi-lugs of composite material for aircraft, according to claim 1, characterized by the fact that the stacks of layers of fibers (20), forming each element (15, 16 , 17), comprise reinforcers (19). 3. Method for the manufacture of a torsion box structure of integrated multilongarinas of composite material for aircraft, according to claim 1 or 2, characterized by the fact that the stacks of layers of fibers (20) forming each element (15, 16, 17) be subjected to changes in planes and changes in stacking according to whether they will later form part of a panel (11, 12) of a stringer (9) or of a longitudinal reinforcement (10). Petition 870180012942, of 02/19/2018, p. 15/20 2/2 4. Method for the manufacture of a torsion box structure of integrated multilongarines of composite material for aircraft, according to any one of claims 1 to 3, characterized by the fact that the pile of fiber layers (20) forming each element ( 15, 16, 17) be curved by applying a vacuum and temperature cycle (22), shaping the pile with the desired geometry through a suitable template (21), template that copies its internal geometry. 5. Method for the manufacture of a torsion box structure of integrated multi-lugs of composite material for aircraft, according to any one of claims 1 to 4, characterized in that the strips of unidirectional fibers are of the same material as those of the pile . 6. Method for the manufacture of a torsion box structure of integrated multi-lingual composite material for aircraft, according to any one of claims 1 to 5, characterized in that the unidirectional fiber strips are of a material compatible with the material the stack. 7. Method for the manufacture of a torsion box structure of integrated multi-lugs of composite material for aircraft, according to any one of claims 1 to 6, characterized by the fact that, in the step of joining the different elements (15, 16, 17), in order to mold the integrated multi-length torsion box structure, continuous stacks, corresponding to the pure coatings (18), are introduced outside the mentioned torsion box. Petition 870180012942, of 02/19/2018, p. 16/20 1/5 FIG 4 Fusa »L l \ í J ~ * T ~ 7 FiG2c 2/5 FIG 3 FIG 4 FIG δ 3/5 FIG 6 FIG 7 FIG 8 4/5 FIG 9 FIG 10 FIG 11 5/5 «k FIG 12 FIG 13